Ichthyosis: the skin manifestation of multiple sulfatase deficiency

Niemann-Pick Disease Type C (NPDC) by Mutation of NPC1 and NPC2: Aberrant Lysosomal Cholesterol Trafficking and Oxidative Stress

Cholesterol trafficking is initiated by the endocytic pathway and transported from endo/lysosomes to other intracellular organelles. Deficiencies in cholesterol-sensing and binding proteins NPC1 and NPC2 induce accumulation in lysosomes and the malfunction of trafficking to other organelles. Each organelle possesses regulatory factors to induce cholesterol trafficking. The mutation of NPC1 and NPC2 genes induces Niemann-Pick disease type C (NPDC), which is a hereditary disease and causes progressive neurodegeneration, developmental disability, hypotonia, and ataxia. Oxidative stress induces damage in NPDC-related intracellular organelles. Although studies on the relationship between NPDC and oxidation are relatively rare, several studies have reported the therapeutic potential of antioxidants in treating NPDC. Investigating antioxidant drugs to relieve oxidative stress and cholesterol accumulation is suggested to be a powerful tool for developing treatments for NPDC. Understanding NPDC provides challenging issues in understanding the oxidative stress-lysosome metabolism of the lipid axis. Thus, we elucidated the relationship between complexes of intracellular organelles and NPDC to develop our knowledge and suggested potential antioxidant reagents for NPDC therapy.

Genodermatoses with behavioural sequelae

Children with genodermatoses are at an increased risk of developing behavioural disorders which may impart lasting damage on the individual and their family members. As such, early recognition of childhood mental health disorders via meticulous history taking, thorough physical examination, and disorder-specific testing is of paramount importance for timely and effective intervention. If carried out properly, prompt psychiatric screening and intervention can effectively mitigate, prevent or even reverse, the psychiatric sequela in question. To that end, this review aims to inform the concerned physician of the manifestations and treatment strategies relevant to the psychological sequelae of genodermatoses.

Neonatal Presentations of Metabolic Disorders

Metabolic disorders in a neonate can present with involvement of any organ system and can be challenging to diagnose. A newborn can present with an acute metabolic crisis such as hyperammonemia or seizures needing immediate management, with a more chronic clinical picture such as cholestatic liver disease, or with structural abnormalities such as skeletal manifestations. Early detection of treatable metabolic conditions is important to improve outcomes. Newborn screening has facilitated early detection and initiation of therapy for many metabolic disorders. However, normal testing does not rule out a metabolic disorder and a high index of suspicion should remain when caring for any critically ill neonate without a diagnosis. Whole exome sequencing (WES) or whole genome sequencing (WGS) can be powerful tools in rapid diagnosis of a potentially treatable metabolic condition in a critically ill neonate. This review presents classic clinical presentations of neonatal metabolic disorders and also highlights some uncommon neonatal manifestations of metabolic disorders to improve the recognition and diagnosis of these conditions.

Inherited ichthyosis: Syndromic forms

Among diseases that cause ichthyosis as one of the symptoms, there are some diseases that induce abnormalities in organs other than the skin. Of these, diseases with characteristic signs are regarded as syndromes. Although these syndromes are very rare, Netherton syndrome, Sjögren-Larsson syndrome, Conradi-Hünermann-Happle syndrome, Dorfman-Chanarin syndrome, ichthyosis follicularis, atrichia and photophobia (IFAP) syndrome, and Refsum syndrome have been described in texts as representative ones. It is important to know the molecular genetics and pathomechanisms in order to establish an effective therapy and beneficial genetic counseling including a prenatal diagnosis.

Revised nomenclature and classification of inherited ichthyoses: results of the First Ichthyosis Consensus Conference in Sorèze 2009

BACKGROUND

Inherited ichthyoses belong to a large, clinically and etiologically heterogeneous group of mendelian disorders of cornification, typically involving the entire integument. Over the recent years, much progress has been made defining their molecular causes. However, there is no internationally accepted classification and terminology.

OBJECTIVE

We sought to establish a consensus for the nomenclature and classification of inherited ichthyoses.

METHODS

The classification project started at the First World Conference on Ichthyosis in 2007. A large international network of expert clinicians, skin pathologists, and geneticists entertained an interactive dialogue over 2 years, eventually leading to the First Ichthyosis Consensus Conference held in Sorèze, France, on January 23 and 24, 2009, where subcommittees on different issues proposed terminology that was debated until consensus was reached.

RESULTS

It was agreed that currently the nosology should remain clinically based. "Syndromic" versus "nonsyndromic" forms provide a useful major subdivision. Several clinical terms and controversial disease names have been redefined: eg, the group caused by keratin mutations is referred to by the umbrella term, "keratinopathic ichthyosis"-under which are included epidermolytic ichthyosis, superficial epidermolytic ichthyosis, and ichthyosis Curth-Macklin. "Autosomal recessive congenital ichthyosis" is proposed as an umbrella term for the harlequin ichthyosis, lamellar ichthyosis, and the congenital ichthyosiform erythroderma group.

LIMITATIONS

As more becomes known about these diseases in the future, modifications will be needed.

CONCLUSION

We have achieved an international consensus for the classification of inherited ichthyosis that should be useful for all clinicians and can serve as reference point for future research.

Serial magnetic resonance imaging and neurophysiological studies in multiple sulphatase deficiency

We present serial clinical, magnetic resonance imaging (MRI) and neurophysiological findings of a patient with multiple sulphatase deficiency (MSD), who was first admitted at the age of 9 months, because of psychomotor retardation. MRI demonstrated extensive diffuse symmetrical high signal in the deep white matter of both cerebral hemispheres, as well as of the subcortical white matter and the brainstem, while there was additional enlargement of sulci and subdural spaces and mild atrophy. Assay of arylsulphatase A activity in white blood cell homogenates at the age of 29 months disclosed a marked deficiency of the enzyme, compatible with the diagnosis of early-infantile metachromatic leukodystrophy. During the course of a later admission, the presence of ichthyosis pointed out to the possible diagnosis of MSD; further assays of sulphatases in plasma, leukocytes as well as in cultured fibroblasts, combined with an abnormal excretion of mucopolysaccharides and sulphatides in urine confirmed the diagnosis. Molecular analysis identified a homozygous disease-causing mutation (R349W) of the SUMF1 gene. Serial neurophysiological and MRI studies demonstrated the progressive nature of the disorder (regarding both central and peripheral nervous system), correlating with the clinical deterioration (spastic quadriplegia, optic atrophy and epilepsy) with subsequent death at the age of 4 years.

Mild ichthyosis in a 4-year-old boy with multiple sulphatase deficiency

We report a 4-year-old boy with multiple sulphatase deficiency (MSD). His early health was good. By the end of his first year there were concerns about developmental delay but by 26 months he showed clear evidence of regression in that he was barely able to sit unsupported and had lost all fine motor and communication skills. At that time he also had widespread mild ichthyosis that cleared completely with the use of emollients. The neurological deterioration suggested a diagnosis of metachromatic leucodystrophy, and a reduction in the leucocyte arylsulphatase A activity was detected. The ichthyosis suggested steroid sulphatase deficiency, and a reduction in the leucocyte steroid sulphatase activity was detected. The enzyme deficiency was much less marked for steroid sulphatase than for arylsulphatase A in this boy. This diversity in enzyme activities is typical of MSD and correlates with the mild ichthyosis in this child. This case shows that even mild ichthyosis should prompt measurement of steroid sulphatase activity in a child of either sex with unexplained neurological deterioration.

Lysosomal disorders

Although most lysosomal storage disorders present in infancy or early childhood with a progressive condition often associated with dysmorphism, considerable genetic heterogeneity exists resulting in a range of illnesses that can include a dramatic neonatal presentation. Whilst some conditions present with a characteristic neonatal phenotype (e.g. Niemann-Pick disease type C), the remainder present in a nonspecific way often with non-immune hydrops fetalis. Diagnosis can be helped by appropriate radiological studies and, in some patients, evidence of the storage phenomena can be seen in peripheral blood smears or bone marrow aspirates. Unfortunately, for the majority of affected patients no effective, curative, treatment is possible. New developments in therapy including enzyme replacement therapy and substrate deprivation may improve prognosis in some disorders. It is important to establish an accurate diagnosis, as prenatal testing can then be offered in future pregnancies.

Papulosquamous disorders of the elderly

Several papulosquamous skin conditions occur in the elderly, including inherited and acquired ichthyoses, psoriasis, cutaneous lymphoma, and cutaneous connective tissue diseases. The clinical presentations can be quite helpful in diagnosing these conditions, and confirmatory histology and immunologic testing can often better define the specific entities. Treatment often involves identifying underlying systemic causes, as well as specific approaches based on the diagnosis and severity of clinical presentation.

Unusual clinical presentation in two cases of multiple sulfatase deficiency

Multiple sulfatase deficiency (MSD) is an inborn error of metabolism that combines the clinical features of late infantile metachromatic leukodystrophy and mucopolysaccharidosis. The characteristic biochemical abnormality is a reduction in the activities of several sulfatases, with consequent tissue accumulation of sulfatides, sulfated glycosaminoglycans, sphingolipids, and steroid sulfates. In this study we present two unusual cases of MSD with variable enzymatic deficiency of arylsulfatases A, B, and C. Both patients had ichthyosis, broad thumbs and index fingers, an unusually slow progression of the neurologic symptoms, and lacked the hepatosplenomegaly that is typical of MSD. Olivopontocerebellar atrophy was present and one patient had a large retrocerebellar cyst. Mucopolysaccharides were not detected in the urine from either subject. Leukocyte arylsulfatase A activity in patient 1 was 0.46 nmol/mg protein/hr and in patient 2 was 0.0 nmol/mg protein/hr (normal 0.7-5.0 nmol/mg protein/hr). Leukocyte arylsulfatase B activity in patient 1 was 24 nmol/mg protein/hr and in patient 2 was 22 nmol/mg protein/hr (normal 115-226 nmol/mg protein/hr). Leukocyte arylsulfatase C in patient 1 was 0.30 pmol/mg protein/hr and in patient 2 was 0.28 pmol/mg protein/hr (normal 0.84 pmol/mg protein/hr). In conclusion, these two patients with MSD had mild clinical presentations not previously reported and variable enzymatic deficiency of arylsulfatases A, B, and C.

Pathologic findings of multiple sulfatase deficiency reflect the pattern of enzyme deficiencies

Multiple sulfatase deficiency is a rare metabolic storage disorder that manifests in childhood. It is probably an autosomal-recessive inherited condition, the gene for which has not yet been identified. Clinical features include mental deficiency and a dysmorphic appearance reminiscent of a mucopolysaccharidosis. Unlike most storage disorders, there are multiple deficient enzymes; all are sulfatases, hence the name of the disorder. Biochemical testing reveals accumulation of glycosaminoglycans, sulfatides, and gangliosides in the brain and other tissues of affected patients. In previous accounts of postmortem examinations, white matter histologic and biochemical pathologic findings similar to metachromatic leukodystrophy have been reported. Ganglioside accumulation, secondary to interference with degradative enzyme activity by the accumulating glycosaminoglycans also has been demonstrated. The authors report a case of multiple sulfatase deficiency with only mild deficiencies of the arylsulfatases but with severe deficiencies of iduronate sulfatase and heparan sulfamidase. Pathologic changes were more in keeping with a mucopolysaccharidosis, with minimal white matter changes and deposition of metachromatic material. The authors postulate that the mild leukodystrophic changes but striking features similar to a mucopolysaccharidosis are reflections of the pattern of enzyme deficiency. The pathology of multiple sulfatase deficiency therefore represents an overlap between a leukodystrophy and a mucopolysaccharidosis, with the relative contribution of each pattern apparently depending on the pattern of enzyme deficiency encountered in each patient.